made by "Marconi International Marine Communications Company Limited"
THE MARCONI TYPE 365 series of keys,
much beloved by many merchant marine Radio Officers has a long history.
Sometimes refered as the 'Marconi Classic'.
The first model was the Type 365. The exact year of introduction is unclear but first references to it seem to be in 1935.
Next came the 365A, of which there were two versions, one with roller bearings and the other with sleeve bearings.
They were painted in a variety of shades of blues and grey.
It was common for Radio Officers to remove the paint and polish the brass.
The cover was sometimes used as the radio room ash tray.
The 365B seems to have been introduced in the early 1940s.
Again there were two versions. fitted either with sleeve or roller bearings.
It was fitted with a key-click suppression circuit * comprising two coils at the rear with capacitors and resistors
under the base.
Type 971 vs 365 Keys
The Type 971 was introduced in the late 1940s and continued until the late 1950s
but it proved so unpopular with Radio Officers that the Marconi Company had to bring back the 365 models.
365EZ and 365FZ
In the late 1960s Type 365EZ and FZ keys appeared but differences
between the two models are negligible. An 'FZ' has been noted with
only one coil fitted to the base. These models were fitted with a diecast aluminium cover
made by the Eddystone Company.
The final key made by the Marconi Company was the Type EZ50 but it lacked the 'feel' of the lovely 365.
Sleeve vs Roller Bearings
Some people are of the opinion that early models were fitted with sleeve bearings and that the roller bearings were
introduced later. Others believe that the keys were originally designed with roller bearings
and that the sleeve bearings were introduced during WWII when there was a shortage of roller bearings.
# (article by Wyn Davies in MM74 2001)
* Typical key-click filter
L serves to prevent too rapid a rise of current.
C, charging through R, serves to continue the flow of current momentarily
when key contacts open.